System for diagnosing reagent solution quality and emissions catalyst degradation

Abstract

A system for determining a reagent solution quality indicator includes a reagent solution source for supplying the reagent solution to an emissions catalyst configured to receive a NOx-containing gas therethrough, means for determining a flow rate of NOx reduced from the gas by the catalyst, means for determining a flow rate of the reagent solution into the catalyst, and a control circuit determining the reagent solution quality indicator as a function of the NOx flow rate and the reagent solution flow rate. The system may additionally be configured to diagnose reagent solution quality by configuring the control circuit to monitor the reagent solution quality indicator over time and produce a fault value if the reagent solution quality indicator crosses a reagent quality indicator threshold, and to diagnose the catalyst by producing another fault value if the catalyst capacity point falls outside of a catalyst capacity point threshold.

Description

FIELD OF THE INVENTION[0001]The present invention relates generally to systems for diagnosing reagent solution quality and emissions catalyst degradation, and more specifically to such systems for diagnosing reagent solution quality and emissions catalyst degradation as functions of NOx and reagent solution flow rates.BACKGROUND OF THE INVENTION[0002]Systems for treating exhaust gas produced by an internal combustion engine to reduce exhaust gas emissions in the form of particulates and / or NOx are generally known. Such exhaust gas “aftertreatment” systems may include a selective catalytic reduction system for the purpose of reducing the NOx level of the exhaust gas below a specified maximum NOx level.[0003]A selective catalytic reduction system, or SCR, typically includes a catalytic reducing agent, or reagent, in the form of a reagent solution that is controllably dispensed into the exhaust gas stream produced by the engine before entering a conventional SCR catalyst. The SCR catal...

AI Technical Summary

Problems solved by technology

Prior to dispensing the reagent solution into the exhaust gas stream, there may be opportunities for the solution to become under-concentrated, over-concentrated and / or exposed to contaminants as a result of manufacturing concentration variability, tampering, accidental introduction of improper fluid, mechanical failures or undesirable mechanical operating conditions, and / or environmental degradation.

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